Plant growth sheet structure, natural turf sheet structure, method of growing turf and method of laying turf sheet structure

ABSTRACT

This invention provides a plant growth sheet structure which includes a base web layer and a core layer integrally coupled together in this order, a base web layer, a plant seed holding layer and a core layer integrally coupled together in this order, or a base web layer, a core layer, a plant seed holding layer and a cover web layer integrally coupled together in this order, and is provided at its surface with plant protection projections, and also provides a natural turf sheet structure including a natural turf grown on the plant growth sheet structure. This invention also provides a turf growing method in which a semi-artificial turf sheet structure including an artificial turf portion and a natural turf portion is laid over a concrete wall surface for performing hydroponics of the natural turf portion, and also provides a method of laying a turf sheet structure, in which a similar semi-artificial sheet structure is accommodated in an outdoor accommodating place for growing a natural turf portion, and is transferred to and laid in large-scale facilities on demand.

TECHNICAL FIELD

The present invention relates to a plant growth sheet structure whichcan be laid in grounds such as a general house garden, a bank of ariver, a park and a golf course as well as planting zones of variousbuildings, roads or the like, fields of various sport facilities andothers, and is used for growing plants. The present invention alsorelates to a natural turf sheet structure which is obtained from theabove structure and has a natural turf grown on it.

Also, the present invention relates to a method of growing turfs onconcrete walls of a dam, a retention pond or the like.

Further, the present invention relates to a method of laying a turfsheet structure, and in particular to a method of laying the turf sheetstructure at large-scale facilities.

BACKGROUND ART

When one intends to grow natural turfs, grasses or flowers at a groundsuch as a general house garden, a bank of a river, a park or a golfcourse, or a planting zone of a building, road or the like, he or shedirectly sows plant seeds in the ground or planting zone, or plantsyoung plants therein. An appropriate anti-flow-out fence or the like maybe provided for preventing flow-out of the sowed seeds or planted youngplants as well as applied fertilizer by rain, wind and irrigated water.

In the sport facilities, fields of soil or natural turfs have been usedfor a long time. However, a difficult or laborious work is required formaintaining such fields, so that artificial turfs are now used in manycases.

However, the artificial turf is not suitable to some kinds of sportssuch as a soccer, so that such sports are played on the natural turfeven in these days.

In the sport facilities, however, the field in which the natural turf isdirectly planted in the ground suffers from such problems that it isdifficult to control the growth of the turf, and that a long time isrequired for repairing a turf damaged by the play, which may disablecontinuous use thereof. In view of this, such a method may be used thatnatural turfs which have been grown at another place are laid on aleveled and prepared base ground, and a possible damaged portion can bereplaced with a new turf.

Natural turfs which have been grown at a different place and are cutinto an appropriate size are used for laying them in the sportfacilities and for replacing a damaged turf portion with it, as is wellknown. In connection with this, one can envisage a semi-artificialnatural turf sheet structure which does not use natural soil and can betransferred.

Such a turf sheet structure may be used at grounds such as a generalhouse garden, a bank of a river, a park, a golf course, a hillock and aseaside as well as planting zones of various buildings, roads or thelike.

As an example of a semi-artificial natural turf sheet structure,Japanese Laid-Open Patent publication No. 51-119108 (1976) has discloseda turf mat which can be rolled up and includes a turf growing soil layermade of saw-dust, an underlying mesh mat and a water-proof base sheet ina layered fashion. Also, Japanese Laid-Open Patent publication No.54-117732 (1979) has disclosed a turf sheet in which soil or sand islaid on a net, and a turf is grown on the same. Japanese Laid-OpenPatent publication No. 60-95004 (1985) has disclosed a structure, inwhich a rubber mat or a synthetic resin plate provided with holes arelaid in a place for growing a natural turf, and the holes are filledwith soil, sand, turf runners, fertilizer and water retaining materialfor growing the turf. Japanese Laid-Open Patent publication No. 62-25907(1987) has disclosed a mat which is mainly made of a rock wool holdingturf seeds mixed thereinto. Japanese Laid-Open Patent publication No.63-91015 (1988) has disclosed a planting mat, in which a rock wool isintegrally provided with a frame member having substantially equallyspaced tip ends and a bottom in a matrix form, and turf seeds arecontained in the rock wool. Japanese Laid-Open Patent publication No.2-104216 (1990) has disclosed a long-sheet product in a roll form, inwhich turfs are decomposed and expanded into elongated forms,stripe-shaped runners are arranged on a net having an appropriate meshsize, and their top surfaces are covered with a water-soluble papersheet. Japanese Laid-Open Patent publication No. 3-247204 (1991) hasdisclosed the following natural turf base. A turf growing base member ismade of a mixture of fertilizer and an inorganic light-weight soilmember. Side and lower surfaces of the base member are covered with alower sheet. An upper sheet is arranged on an upper surface of the basemember. A member holding turf seeds are arranged at the lower surface ofthe upper sheet. A wave-shaped net is arranged between the turf seedholding member and the lower sheet and in the base member. The upper andlower sheets are integrally joined together by sewing threads, staplesor the like.

However, when one intends to grow natural turfs, grasses or flowers at aground such as a general house garden, a bank of a river, a park, a golfcourse, a hillock washed with rainwater, or a seaside exposed to astrong wind, or at a planting zone of a building, road or the like bydirectly sowing plant seeds in the ground or planting zone, or plantingyoung plants therein, such a problem arises that the sowed seeds orplanted young plants as well as applied fertilizer and others are liableto be flown out by rainwater, wind, irrigated water and others. Althoughthe above problem can be prevented by provision of an anti-flow-outfence, or the like, this requires a laborious and time-consuming work.

Each of the natural turf sheet structures disclosed in the foregoingpublications can be used without cutting it or after cutting it into anappropriate size. Further, it may be cut into an appropriate size aftergermination of turf seeds or growth, if necessary. Thereby, it can belaid over grounds such as a general house garden, a bank of a river, apark and a golf course as well as a place such as a planting zone of abuilding or a road, in which case the foregoing problems caused bydirect sowing in the soil can be prevented to a certain extent. Also,the above structures can be used in sport facilities. However, thefollowing problem arises.

The perforated rubber mat and synthetic resin plate disclosed inJapanese Laid-Open Patent publication No. 60-95004 are used not forentirely growing the turf but for intermittently growing the turf.Therefore, this cannot be employed when the turf is to be grown on awhole surface without a space. Particularly, this cannot be employed insport facilities.

Further, except for the natural turf base, which includes the upper andlower sheets fixed together by the sewing threads, staples or the likeas disclosed in Japanese Laid-Open Patent publication No. 3-247204, thestructures disclosed in the foregoing publications cannot be used forthe places such as sport facilities in which a severe force is appliedthereto, because these structures are liable to be entirely decomposedand/or damaged. If the turf is damaged, e.g., by being shaved, anunderlying material is exposed to exhibit an unpreferable appearance.

Even in the natural turf base disclosed in Japanese Laid-Open Patentpublication No. 3-247204, if the turf is damaged, e.g., by being shaved,an underlying material is exposed, which similarly results in anunpreferable appearance.

Further, any of the natural turf sheet structures disclosed in theforegoing publications suffers from a problem that its weight is smalland/or it cannot be sufficiently fitted with the underlying soil or thelike, resulting in a poor stability. Therefore, a problem arises when itis laid, for example, over an inclined surface of a river bank, hillockor the like. Particularly, it is not suitable to the sport facilities,because players cannot stably play on the structure.

Description has been given on the case where the plants such as a turfare grown in grounds such as a general house garden, a bank of a river,a park and a golf course as well as planting zones of various buildings,roads or the like, fields of various sport facilities and others. Inaddition to these places, it is preferable to plant the natural turf atconcrete walls of concrete constructions such as a concrete dam in somecases in order to protect the construction and/or improve an appearance.

Generally, dams are used for irrigation and water control, and morespecifically, for storing water for electric power generation,irrigation, public water, industrial water or the like, and/or forpreventing flood or controlling a water level. As a kind of dam, therehas been a concrete dam constructed from concrete.

Generally, outer surfaces or walls of the concrete dam are not finishedor coated. However, the unfinished concrete surface is directly exposedto the sunshine, wind and rain, so that they are liable to bedeteriorated. In order to prevent the deterioration, outer finishing maybe effected on the concrete surface as is done in ordinary buildings.However, the concrete dam, which is a huge construction, requires a vastsum of money for finishing its outer surfaces, so that the outersurfaces are not actually finished.

Some of huge dams are tourist attractions, in which case unfinishedconcrete surfaces of the dams present an unpreferable scene and sense ofincompatibility with respect to surrounding green.

As measures for the above, it may be envisaged to cover the concretesurfaces, e.g., of the concrete dam with a natural turf sheet. However,appropriate method and technique for the above have not been proposed.

In addition to the foregoing, the following problem actually arises whenone intends to lay turfs or the like.

In many large-scale facilities such as indoor sport facilities,gymnasiums and other multipurpose holes, an artificial turf is laid andremoved depending on contents of the games and events. In this case, aproblem actually arises in connection with storage of huge artificialturfs, which are to be laid in large-scale facilities. For example, if awarehouse for storing the artificial turfs cannot be ensured in thelarge-scale facilities, the warehouse must be independently prepared forstoring them. If the independent warehouse is remote from thelarge-scale facilities, a time-consuming work is required fortransferring the artificial turfs between the warehouse and thelarge-scale facilities. Further, the artificial turf is worn inaccordance with use, and is considerably damaged when it is used forhard sport games such as a soccer. Therefore, the artificial turfrequires a time-consuming repair.

Accordingly, a first object of the invention is to provide a plantgrowth sheet structure of a first type for growing a plant such as aturf which has the following advantages.

(1-1) Without changing a size or after cutting the structure into anappropriate size, the structure can be simply and easily laid in groundssuch as a general house garden, a park, a river bank, a golf course, ahillock washed with rainwater and a seaside exposed to a strong wind aswell as planting zones of various kinds of buildings, roads or the like,sport facilities and others. Also, it is possible to sow seeds of turfs,grasses and flowers, and grow them in the structure. Also, the structurecan be moved to and from the above places.

(1-2) Sowed seeds, sprouts growing therefrom and others are suppressedfrom being moved and flowed out by the wind, rain, irrigated water orthe like, which facilitates growth and maintenance of the plants.

(1-3) The whole structure is integral and has a sufficient resistanceagainst decomposition. Sowed seeds as well as sprouts, roots and othersare protected against a downward load, a lateral pulling force or thelike, which also facilitates maintenance of growing and grown plants.

(1-4) It is possible to suppress an unpreferable appearance beforegrowing of plants and even in such a case that grown plants are damagedor lost due to shaving or withering.

(1-5) The structure can be laid over possible seeds of weeds to restrictgrowth thereof, which also facilitates maintenance of growing and grownplants.

(1-6) A weight can be controlled, and thus its weight can be reduced toallow easy transfer. Also, the weight can be increased to improvestability of the laid structure at an installation place. The stabilityof the laid structure can be improved to allow use in sport facilitiesfor some kinds of sports.

(1-7) The structure can be produced in an elongated form.

A second object of the invention is to provide a plant growth sheetstructure of a second type, which holds seeds of plant such as turfseeds in advance, and has the following advantages.

The “turf seeds” mean the seeds of turf themselves as well as runners orthe like which are obtained from cut turfs or the like, and from which aturf can be obtained.

(2-1) Without changing the size, or after cutting the structure into anappropriate size, the structure can be easily laid in grounds such as ageneral house garden, a river bank, a park, a golf course, a hillockwashed with rainwater, and a seaside exposed to a strong wind as well asplanting zones of various buildings, roads or the like, sport facilitiesand others. It is possible to grow plants from seeds of turf, grass orflower which are held in advance at the structure. Also, the structurecan be moved to and from the above places.

(2-2) The plant seeds held at the structure, sprouts growing therefromand others are suppressed from being moved or flowed out by the wind,rain, irrigated water or the like, which facilitates growth andmaintenance of plants.

(2-3) The whole structure is integral and has a sufficient resistanceagainst decomposition. Held seeds as well as sprouts, roots and othersare protected against a downward load, a lateral pulling force or thelike, which also facilitates maintenance of growing and grown plants.

(2-4) The structure also has advantages similar to those alreadydescribed at the items (1-4) through (1-7) of the plant growth sheetstructure of the first type.

A third object of the invention is to provide a natural turf sheetstructure having the following advantages.

(3-1) Without changing the size, or after cutting the structure into anappropriate size, the structure can be easily laid in grounds such as ageneral house garden, a park, a river bank, a golf course, a hillock anda seaside as well as planting zones of various buildings, roads or thelike, sport facilities and others. Also, the structure can be easilymoved to and from the above places.

(3-2) The turf is suppressed from being moved or flowed out by the wind,rain, irrigated water or the like, which facilitates growth andmaintenance of turfs.

(3-3) The whole structure is integral and has a sufficient resistanceagainst decomposition. Sprouts, roots and others of the turf areprotected against a downward load, a lateral pulling force or the like.Therefore, the structure can be used in the sport facilities. This alsofacilitates maintenance of the turf.

(3-4) As compared with a conventional natural turf sheet structure, itis possible to suppress an unpreferable appearance in such a case thatturfs are damaged or lost due to shaving or withering.

(3-5) The structure can be laid over possible seeds of weeds to restrictgrowth thereof, which also facilitates maintenance of turfs.

(3-6) A weight can be controlled, and thus its weight can be reduced toallow easy transfer. Also, the weight can be increased to improvestability of the laid structure at an installation place. The stabilityof the laid structure can be improved to allow use in sport facilitiesfor some kinds of sports.

(3-7) The structure can be produced in an elongated form.

A fourth object of the invention is to provide a method of growing aturf, in which a turf is grown at a concrete surface of a concrete dam,a retention pond or the like for covering the concrete surface with anatural turf so as to protect the surface against the direct sunshine,wind and rain, and to improve an appearance thereof.

A fifth object of the invention is to provide a method of laying a turfsheet structure, and in particular to a method of laying a turf sheetstructure in large-scale facilities, by which it is possible to performstorage of the turf sheet structure before and after intendedarrangement of the same, laying of the stored structure for the intendedarrangement, and restoring and rearranging of the damaged turf sheetstructure in a more simple and economical manner than a conventionalartificial turf.

DISCLOSURE OF THE INVENTION

A plant growth sheet structure for growing a plant such as a turfaccording to the invention for achieving the first object (i.e., theplant growth sheet structure of the first type) is characterized in thata base web layer and a core layer are layered in this order along anascending direction and are integrally coupled together; the base weblayer has a water retentivity; and the core layer has a large number ofgaps providing water and gas permeabilities, has a form-maintainingproperty, and is provided at its surface with a large number of flexibleplant protection projections.

A plant growth sheet structure for growing a plant such as a turfaccording to the invention for achieving the second object (i.e., theplant growth sheet structure of the second type) may be either of thefollowing plant growth sheet structures of two types, i.e., type 2(1)and types 2(2).

The plant growth sheet structure of the type 2(1)

The plant growth sheet structure for growing a plant such as a turf ischaracterized in that a base web layer, a plant seed holding layer forholding and germinating plant seeds such as turf seeds, and a core layerare layered in this order along an ascending direction and areintegrally coupled together; the base web layer has a water retentivity;and the core layer has a large number of gaps providing water and gaspermeabilities, has a form-maintaining property, and is provided at itssurface with a large number of flexible plant protection projections.

The plant growth sheet structure of the type 2(2)

The plant growth sheet structure for growing a plant such as a turf ischaracterized in that a base web layer, a core layer, a plant seedholding layer for holding and germinating plant seeds such as turfseeds, and a cover web layer allowing growth of plants from the plantseeds are layered in this order along an ascending direction and areintegrally coupled together; the base web layer has a water retentivity;the core layer has a large number of gaps providing water and gaspermeabilities, and has a form-maintaining property; and the cover weblayer is provided at its surface with a large number of flexible plantprotection projections.

A natural turf sheet structure according to the invention for achievingthe third object may be one of the following structures.

A natural turf sheet structure (i.e., natural turf sheet structure of a1L type) which is obtained from the plant growth sheet structure of thetype 1 already described and has a natural turf grown from turf seedssowed in it.

A natural turf sheet structure (i.e., natural turf sheet structure of a2(1)L type) which is obtained from the plant growth sheet structure ofthe type 2(1) already described and has a natural turf grown from turfseeds held as plant seeds in it.

A natural turf sheet structure (i.e., natural turf sheet structure of a2(2)L type) which is obtained from the plant growth sheet structure ofthe type 2(2) already described and has a natural turf grown from turfseeds held as plant seeds in it.

In any of the structures, the “turf seeds” mean the seeds of turfthemselves as well as runners or the like which are obtained from cutturfs or the like, and from which a turf can be obtained.

In any of the plant growth sheet structures and the natural turf sheetstructures described above, the base web layer employed therein isessentially required only to have the water retentivity, which allowsabsorption of water, which is, for example, applied or poured to thestructure, or in which the structure is immersed. By controlling thewater retentivity, the weights of the plant growth sheet structure andthe natural turf sheet structure of the invention can be controlled.Also, by controlling the water retentivity, it is possible to control anamount of water supplied to seeds, sprouts and grown plants, e.g., of anatural turf. Further, by adding nutrient into the water retainedtherein, it is possible to control an amount of nutrient to be supplied.The amount of retained water can be desirably controlled not only bycontrolling an amount of water supplied to the structure but also bydischarging the water by compressing, squeezing or tilting thestructure. In any case, it is desired to provide a flexibility at thebase web layer so as to improve a fitting property of the plant growthsheet structure and the natural sheet structure of the invention withrespect to a place for installation.

For example, the base web layer may be a web layer formed of anappropriate kind of entangled fibers (e.g., cotton fibers), a fabric ofan appropriate kind of fibers, a knit or a combination of them.

Among them, the cotton web layer is desirable because it has a goodwater absorption and a good water retentivity, and allows easydischarging of water, e.g., by compressing or squeezing the same so thatthe weight can be controlled easily. Also, it allows easy controll ofthe amount of retained water so that the amount of water supplied toseeds, sprouts and grown plants of the natural turf or the like can becontrolled easily. Further, by preparing the water containing nutrient,it allows easy control of the amount of nutrient to be supplied.

When the base web layer is a cotton web layer, it may be made of naturalcotton, synthetic fiber cotton or combination of them. In order to allowcontrol of the water retentivity in a wide rage, the cotton may beentirely or partially a water-absorbing cotton made of water-absorbingfibers. For example, the layer may be made of mixture of synthetic fibercotton and water-absorbing cotton. For example, this synthetic fibercotton may be made of polyester or acrylic fibers of about 2 to 8deniers. For example, the water-absorbing cotton may be made ofsuper-water-absorbing fibers (trade name: Runseal F) manufactured byToyo Bouseki Co. Ltd.

In any of the plant growth sheet structures and the natural turf sheetstructures already described, the core layer employed therein isessentially required only to have gaps, e.g., in a continuous formproviding water and gas permeabilities in order to allow sufficientgermination of the plant seeds and subsequent growth, and to have aform-maintaining property. Further, the core layer is desired to ensurean intended strength of the plant growth sheet structure or the naturalturf sheet structure. For example, it may be a have a mesh form, andspecifically, may be a three-dimensional mesh structure formed ofentangled synthetic resin fibers, a mesh basket structure formed ofsynthetic resin fibers, a series of small mesh basket structures, asingle mesh plate made of synthetic resin fibers or the like, or aplurality of layered mesh plates formed of synthetic resin fibers. Itmay also be formed of the above mesh core layer loaded with bulkmaterial, saw-dust, wood pieces or the like, or a mesh or cloth bagsaccommodating bulk material, saw-dust, wood pieces or the like. In anycase, it is desirable that the core layer has a flexibility so as toimprove a fitting property of the plant growth sheet structure ornatural turf sheet structure with respect to an installation place.Additionally, it is desirable that the core layer has an appropriateelasticity for improving a feeling of an athlete or player who walks orplays on the structure (particularly, in the case of the natural turfsheet structure).

The three-dimensional mesh structure formed of entangled synthetic resinfibers is desirable because it has an appropriate flexibility and anappropriate elasticity as well as a large number of gaps and anappropriate strength. Particularly, the three-dimensional mesh structuremay be preferably formed of entangled synthetic resin fibers of about0.1 mm to about 0.8 mm in diameter made of, e.g., polyamide,polypropylene or polyvinyl chloride.

The foregoing three-dimensional mesh structure may be a mesh structure(e.g., trade name: Zeomat 7020) manufactured by Zeon Chemical Co., Ltd.

In any case, at least the surface of the core layer may be colored, forexample, similarly to the color of a plant (e.g., green, or mixedstripes of brown and green) so as to prevent remarkable impairment of anappearance by the core layer in such cases that, in the plant growthsheet structure of the above type 1, plants have not yet grown fromsowed seeds or grown plants are shaved off or wither, that, in the plantgrowth sheet structure of the above type 2(1), plants have not yet grownfrom seeds in the plant seed holding layer or grown plants are shavedoff or wither, and that a turf on the natural turf sheet structure ofthe invention obtained from the above plant growth sheet structure isshaved off or withers.

In the plant growth sheet structures of the above type 2 (type 2(1) and2(2)), the plant seed holding layer is essentially required only to holdthe plant seeds such as turf seeds without allowing movement thereof soas to allow germination, and it is desired that the plant seeds aredispersed as uniformly as possible. For example, this plant seed holdinglayer may include a non-woven fabric sheet allowing germination of plantseeds and subsequent growth, the plant seeds uniformly dispersed on thenon-woven fabric sheet, and a water-soluble seed retaining film coveringthe plant seeds without preventing germination of the plant seeds andthe subsequent growth. The water-soluble film retaining seeds may bemade of a protein material, a starch material or the like, and maycontain germination nutrient. Alternatively, the plant seed holdinglayer may include a base sheet, e.g., made of a non-woven fabric sheetand dispersed plant seeds adhered to the base sheet by adhesive. In anycase, it is desired that it has a flexibility as a whole so as toprovide a good fitting or mating property with respect to the core layerand base web layer (in the case of type 2(1)), or the core layer and thecover web layer (in the case of type 2(2)). The non-woven fabric sheetand the base sheet may have a water resistance or a water-solubility,and may also have another property.

The cover web layer in each of the plant growth sheet structure of thetype 2(2) and the natural turf sheet structure obtained therefrom areessentially required to have the following features. In the plant growthsheet structure, it is required to allow germination of the plant seedsat the plant seed holding layer and subsequent growth, and is desirablyrequired to protect the plant seeds. In the natural turf sheetstructure, it is required to allow growth or the like of plants, and isalso desirable to provide a water retentivity. Further, it is desired toallow control of the amount of retained water. In view of the above, theweb may be, for example, a layer made of cotton, a fabric of variouskinds of fibers, a knit or a combination of them. Among them, the cottonweb layer is one of the desirable webs because it has goodwater-absorbing and retaining properties and allows easy control of theamounts of water and nutrient to be supplied. In the case where thecotton web layer is employed, the cotton may be natural cotton,synthetic fiber cotton or combination of them, and, similarly to thebase web layer, may be partially or entirely formed of water-absorbingcotton made of water-absorbing fibers (e.g., foregoing Runseal F).

In the plant growth sheet structure of the type 2(2), the base web layerand the cover web layer may be made of cotton web layers, in which casea quantity of cotton of the cover web layer may be smaller than that ofthe base web layer to form the cover web layer thinner than the base weblayer, so that the cover web layer may not impede germination of theplant seeds and subsequent growth. Meanwhile, the base web layer isdesired to have a thickness which allows control of the quantity ofretained water, and thereby allows control of the weight of the base weblayer and the quantity of water supplied to plants in an intended range.

The base web layer and the cover web layer may be mutually coupled bythreads or the like. In connection with this, the base web layer and thecover web layer made of cotton may be coupled together by mutuallyentangling and coupling some of cotton fibers forming these layersthrough the core layer and the plant seed holding layer. Coupling ofthese cotton webs may be performed by a needle punch method, which isknown as a general web joining method, with the core layer and the plantseed holding layer arranged therebetween. In addition to the abovemanner, threads or another coupling means may be employed.

In the plant growth sheet structure of the type 1 and the plant growthsheet structure of the type 2(1) as well as the natural turf sheetstructures obtained therefrom, the base web layer and the core layer maybe mutually coupled by threads or another means. In connection withthis, if the base web layer is made of cotton, both the layers may becoupled together by entangling some of the cotton fibers forming thebase web layer with the core layer, and threads or another couplingmeans may be additionally employed.

In any of the plant growth sheet structures and natural turf sheetstructures described above, a backing member may be arranged at thelower portion of the web layer for one or more of purposes of protectionof the base web layer, shape-maintaining, control of a cushioningproperty of the structure, control of a weight of the structure andothers. The backing member which has a sheet form may be adhered to thelower surface of the base web layer, may be laid over and coupled to thebase web layer by a coupling means such as threads, or may be arrangedby combination of the above manners. Alternatively, the backing membermay be molded into a sheet-like form at the lower portion of the baseweb layer. Another manner may also be employed, and, for example, abacking material may be applied to the lower surface of the base weblayer.

The backing member is arranged to allow water flow between the base weblayer and its exterior, if the plant growth sheet structure and thenatural turf sheet structure of the invention are of a permanent typeand thus are permanently arranged at places. If they are of a temporarytype and thus may be transferred, it may be unnecessary to allow thewater flow. Whichever type it may be, the backing member may be arrangedto allow water flow between the base web layer and its exterior in orderto allow utilization of moisture or water in the soil or the like atwhich the structure of the invention is arranged, to improve drainage ofthe structure, to discharge surplus moisture or water from the structureand/or to achieve another effect. In this case, the backing memberitself may or may not have a water permeability. Even if the backingmember does not have a water permeability, a plurality of backingmembers may be arranged intermittently, so that water flow is allowedbetween the base web layer and its exterior.

In any case, the backing member arranged at the base web layer partiallyor entirely may be made of a water-soluble material containingfertilizer. In this case, external supply of nutrient can be reduced oreliminated depending on the amount and kind of the fertilizer, so thatit is possible to reduce the maintenance work.

In the plant growth sheet structure of the above type 1 and the naturalturf sheet structure of the invention obtained therefrom as well as theplant growth sheet structure of the above type 2(1) and the natural turfsheet structure of the invention obtained therefrom, the core layer isprovided at its surface with a large number of flexible plant protectionprojections. In the plant growth sheet structure of the above type 2(2)and the natural turf sheet structure of the invention obtainedtherefrom, the cover web layer is provided at the surface with flexibleplant protection projections. The protection projection may be formed ofa fiber member, which is provided for forming the protection projectionand is made of synthetic resin, natural material, combination thereofand other materials. The fiber member may be attached to the surface ofthe core layer or cover web layer by adhesion, binding or weaving.Alternatively, the fiber member for forming the protection projectionmay be woven through the core layer into the base web layer, or throughthe cover web layer into the base web layer. In this manner, the fibermember forms the plant protection projection at the surface of the corelayer or the cover web layer. In this case, the fiber member cancontribute by itself or together with another connecting means such asthreads to integral coupling between the base web layer and the corelayer, integral coupling of the base web layer, core layer and plantseed holding layer located therebetween, or integral coupling of thebase web layer, core layer, plant seed holding layer and cover weblayer.

In the structure where the fiber member for forming the plant protectionprojection is woven through the core layer into the base web layer sothat the fiber member forms the plant protection projection at thesurface of the core layer, or in the structure where the fiber memberfor forming the plant protection projection is woven through the coverweb layer into the base web layer so that the fiber member forms theplant protection projection at the surface of the cover web layer, thebacking member may be used also as a member which acts at leastpartially on a portion of the fiber member woven into the base web layerfor preventing disengagement. In this structure, the backing member maynot be merely fitted onto the base web layer, but may be adhered to thelower surface of the base web layer, or may be molded into a sheet-likeform at the lower portion of the base web layer, or may be formed byapplying a backing material to the lower surface of the base web layerfor fixing the fiber member, i.e., for disengagement. The backing membermay be provided for one or more of the above purposes such as protectionof the base web layer, shape maintaining, control of a cushioningproperty of the structure, control of the structure weight and others,and as described above additionally for the purpose of prevention ofdisengagement of the fiber member. However, the major purpose of thebacking member may be only prevention of disengagement of the fibermember, although it may additionally achieve one or more of protectionof the base web layer, shape maintaining, control of a cushioningproperty of the structure, control of the structure weight and others.

In any case, pile yarns may be employed as the fiber members for formingthe plant protection projections, and in this case the protectionprojection may be formed of, for example, a pile projection such as acut pile or a loop pile of a carpet, or may be formed of a pile-likeprojection, e.g., formed by a chain stitch.

Regardless of whether the fiber members are made of the pile yarns ornot, the plant protection projections formed at the surfaces of the corelayer and the cover web layer are essentially required only to have astrength (e.g., tensile strength), a toughness or the like which allowprotection of the sowed plant seeds or the plant seeds held at the plantseed holding layer, sprouts and roots growing from the seeds, and grownplants. The fiber member may be formed of a single fiber, a bundle of aplurality of fibers, a plurality of twisted monofilaments or the like.For example, it may be a large-denier filament yarn, e.g., of polyamide,polyethylene or polyester.

In any case, the fiber member for forming the plant protectionprojection may have a water transferring property regardless of whetherit is a pile yarn or not. Employment of the fiber member having thewater transferring property facilitates maintenance such as growth ofplants. Typically, the fiber member having the water transferringproperty can be selected from various kinds of fiber members having thewater transferring property achieved by a capillary phenomenon. It maybe a twisted monofilament disclosed in the international publicationWO90/15193 based on the international patent application under P.C.T.,which has a spiral section and has a good water retentivity and a goodwater transferring property for an artificial turf.

In any case, a height of the plant protection projection from thesurface of the core layer or the cover web layer is determined to allowthe grown plant to project above the protection projection, and in viewof protection of the seeds, roots or the like of the plants. Forexample, if the plant is a turf, the height may be about 3 mm to about15 mm, and preferably about 5 mm to about 7 mm, although it is notrestricted to these values. The density of the plant protectionprojections at the surfaces of the core layer or the cover web layer isdetermined in an appropriate range which allows protection of the seeds,roots and others of the plants, and does not impede growth of theplants.

In any case, the protection projections may be colored, for example,similarly to the color of a plant (e.g., green, or mixed stripes ofbrown and green) so as to prevent remarkable impairment of an appearanceby the plant protection projections in such cases that, in the plantgrowth sheet structure, plants have not yet grown or grown plants areshaved off or wither, and that, in the natural turf sheet structure, theturf is shaved off or withers.

In the plant growth sheet structure and the natural turf sheet structureof the invention, the base web layer, the core layer, the plant seedholding layer (if provided) and the cover web layer (if provided) may beflexible to allow rolling or winding of the entire structure forfacilitating transfer and storage.

The plant growth sheet structure of the type 1 achieving the above firstobject and the natural turf sheet structure obtained therefrom as wellas the plant growth sheet structures of the type 2 (types 2(1) and 2(2))achieving the above second object and the natural turf sheet structureobtained therefrom can be easily laid on grounds such as a general housegarden, a park, a river bank, a golf course, a hillock, and a seaside aswell as planting zones of various buildings, roads and others, sportfacilities, another place and facilities dedicated for growing thenatural turf sheet structure or the like from the plant growth sheetstructure. If necessary, the structures are transferred to and from theabove places.

In the plant growth sheet structure of the type 1, plant seeds of aturf, grass, flower or the like are sowed, and water containing or notcontaining plant growing nutrient is supplied thereto under anappropriate temperature condition, so that the base web layer absorbsand retains the water, and the seeds germinate and grow to intendedplants.

In the plant growth sheet structure of the type 2, water containing ornot containing plant growing nutrient is supplied thereto under anappropriate temperature condition, so that the base web layer absorbsand retains the water, and the seeds held in advance at the structuregerminate and grow to intended plants.

In any of the natural turf sheet structure of the invention, watercontaining or not containing plant growing nutrient is supplied thereto,so that the base web layer absorbs and retains the water, and the turfis maintained and grows.

If a plurality of structures, each of which is the same as the plantgrowth sheet structures or the natural turf sheet structures and has anappropriate size, are arranged in an aligned form, adjacent structuresare mutually coupled, e.g., by machine-sewing the base web layers, ifnecessary. This coupling improves the installation stability of thestructures. When a plurality of structures of an appropriate size arearranged in contact with each other (particularly, when the base weblayers are arranged in contact with each other), the water containing ornot containing growth nutrient may be partially supplied to them, inwhich case the base web layers function as water passages, so that thewater (and nutrient) are uniformly and entirely supplied to them, whichfurther facilitates the maintenance of plants. Roots of the grown plantsmay reach the base web layers to absorb therefrom the water (andnutrient in the water).

In the plant growth sheet structure of the type 1, the sowed seeds arelocated between the plant protection projections at the surface of thecore layer, or are located in the core layer, and the seeds thus locatedhardly move therefrom, and are stably held thereat. Therefore, thesprouts and roots growing from the seeds are substantially held stablyat the same positions, so that the sowed seeds as well as the sproutsand roots growing therefrom are suppressed from being moved and flowedby the wind, rain, irrigated water and others. In the natural turf sheetstructure obtained from the above structure, the turf roots extendbetween the protection projections and further into the core layer, sothat the turf is suppressed from being moved and flowed out by the wind,rain, irrigated water and others.

In the plant growth sheet structures of the type 2 provided with theplant seed holding layer, the plant seeds are stably held at the plantseed holding layer, and the sprouts and roots growing from the seeds aresubstantially held stably at the same positions. Therefore, the seeds aswell as the sprouts and roots growing therefrom are suppressed frombeing moved and flowed by the wind, rain, irrigated water and others. Inthe natural turf sheet structure obtained from the structure of the type2(1), the turf roots extend through the core layer and the base weblayer and further between the protection projections, so that the turfis suppressed from being moved and flowed out by the wind, rain,irrigated water and others. In the natural turf sheet structure obtainedfrom the structure of the type 2(2), the roots of the grown turf extendthrough the core layer and further reach the base web layer, so that theturf is suppressed from being moved and flowed out by the wind, rain,irrigated water and others.

In any of the plant growth sheet structure and the natural turf sheetstructure of the invention, the whole structure is integral, and issuppressed from being decomposed by an external force. Further, theplant protection projections are arranged at the surface of the corelayer or the cover web layer. In the plant growth sheet structure,therefore, the sowed seeds of plants or the plant seeds held in advanceat the plant seed holding layer as well as the sprouts and roots growingtherefrom are protected against a downward load, a lateral pulling loadand others applied from a position above the protection projections.Also in the natural turf sheet structure, the sprouts and roots of theturf are protected against a downward load, a lateral pulling load andothers. In particular, the plant growth sheet structure of the type 2(2)provided with the cover web layer and the natural turf sheet structureobtained therefrom are suitably used in places such as sport facilitiesin which a severe external force is applied thereto.

The plant protection projections arranged at the surfaces of the corelayer and the cover web layer as well as the surfaces of the core layerand the cover web layer may be colored appropriately, so that it ispossible, in the plant growth sheet structure, to prevent impairment ofan appearance even in such a case that plants have not yet grown fromthe sowed or held seeds, or grown plants are damaged or lost due toshaving, withering or the like, and it is possible, in the natural turfsheet structure, to prevent impairment of an appearance even in such acase that the turf is damaged or lost due to shaving, withering or thelike.

In any of the plant growth sheet structure and the natural turf sheetstructure of the invention, the base web layer may be laid to press downpossible seeds of weeds under the same, so that growth of unpreferableweeds can be prevented by laying the base web layer in this manner.

In any of the plant growth sheet structure and the natural turf sheetstructure of the invention, the whole weight of the structure can becontrolled by controlling, e.g., the amount of water supplied to thebase web layer and thereby controlling the amount of water retainedtherein. By this weight control, the whole weight can be reduced forfacilitating transfer of the structure. It is also possible to improvethe installation stability of the structure at the intended place.Although depending on the kind of sport, it is possible to achieve theinstallation stability to allow use at sport facilities.

In any of the plant growth sheet structure and the natural turf sheetstructure, it is possible to produce the structure in an elongated form.

A turf growing method of the invention achieving the fourth object ischaracterized in that a semi-artificial turf sheet structure includingan artificial turf portion and a natural turf portion is laid. over aconcrete wall surface, and hydroponics of the natural turf portion isperformed by supplying water with or without nutrient to thesemi-artificial turf sheet structure.

The above semi-artificial turf sheet structure is essentially requiredonly to include the artificial turf portion and the natural turfportion. For example, the foregoing plant growth sheet structure of thetype 2 and the natural turf sheet structure obtained therefrom may beemployed as the foregoing semi-artificial turf sheet structure or asemi-artificial turf sheet structure piece. In this case, the plantprotection projection in the structure can be used as the artificialturf portion, and the turf seeds held at the plant seed holding layerand the natural turf growing therefrom can be used as the natural turfportion.

More specifically, the following structures may be examples of thesemi-artificial turf sheet structure.

(α) The semi-artificial turf sheet structure is formed of a plurality ofplant growth sheet structures, each of which corresponds to the plantgrowth sheet structure of the type 2(1), and has such features that abase web layer, a plant seed holding layer for holding and germinatingturf seeds, and a core layer are layered in this order along anascending direction and integrally coupled together, that the base weblayer has a water retentivity, and that the core layer has a largenumber of gaps providing water and gas permeabilities, has aform-maintaining property, and is provided at its surface with a largenumber of flexible plant protection projections. Alternatively, thesemi-artificial turf sheet structure is formed of a plurality of naturalturf sheet structures, each of which includes the turf grown from theabove plant growth sheet structure and corresponds to the natural turfsheet structure of the type 2(1)L.

(β) The semi-artificial turf sheet structure is formed of a plurality ofplant growth sheet structures, each of which corresponds to the plantgrowth sheet structure of the type 2(2), and has such features that abase web layer, a core layer, a plant seed holding layer for holding andgerminating turf seeds, and a cover web layer are layered in this orderalong an ascending direction and are integrally coupled together, thatthe base web layer has a water retentivity, that the core layer has alarge number of gaps providing water and gas permeabilities, and has aform-maintaining property, and that the cover web layer is provided atits surface with a large number of flexible plant protectionprojections. Alternatively, the semi-artificial turf sheet structure isformed of a plurality of natural turf sheet structures, each of whichincludes the turf grown from the above plant growth sheet structure andcorresponds to the natural turf sheet structure of the type 2(2)L.

The foregoing concrete wall surface may be, for example, a concrete wallsurface of a dam, a retention pond or the like.

According to the turf growing method of the invention, thesemi-artificial turf sheet structure including the artificial turfportion and the natural turf portion is laid over the concrete wallsurface, and the water with or without the nutrient is supplied to theturf sheet structure thus laid, so that hydroponics can be performed atthe natural turf portion, and thereby a natural turf can be laid overthe concrete wall surface. Since the concrete wall surface is coveredwith the turf sheet structure and thus is not directly exposed to thesunshine, wind and rain, deterioration of the concrete wall surface canbe prevented. The concrete wall surface can be easily greened.

If the concrete wall surface is a surface of a dam, water stored in thedam can be supplied to the laid semi-artificial turf sheet structuretogether with nutrient, if necessary, so that growth of the natural turfportion can be performed easily.

As described above, the concrete wall of the concrete dam can be greenedto improve a landscape by harmonizing the same with a surrounding green.Owing to this greening, the concrete dam can be utilized as one ofsights in a sight-seeing route.

In the structure where water stored in the dam is supplied to thesemi-artificial turf sheet, pipings may be arranged at the concrete wallsurface to be covered with the turf sheet structure so that water may besupplied to the structure through sprinklers provided at the pipings.Alternatively, a runner or mobile unit which is movable on the concretesurface and stores water may be arranged for supplying water from therunner.

If the concrete wall surface is a concrete wall surface of a retentionpond, water stored in the retention pond can be supplied to thesemi-artificial turf sheet structure together with nutrient, ifnecessary, so that growth of the natural turf portion can be performedeasily.

If the retention pond and its surrounding area are to be utilized as aplace for recreation, the turf sheet structure covering the concretewall surface of the retention pond provides a place suitable torecreation.

A method of laying a turf sheet structure for achieving the fifth objectof the invention is characterized in that a semi-artificial turf sheetstructure including an artificial turf sheet portion and a natural turfsheet portion is laid and kept at an outdoor accommodating place locatedoutside large-scale facilities while growing a turf, the turf sheetstructure is transferred to and laid in the large-scale facilities ondemand, and when the semi-artificial turf sheet structure laid in thelarge-scale facilities is to be removed, the turf sheet structure ismoved by transferring the same to the outdoor accommodating placeoutside the large-scale facilities and laying the same in the outdooraccommodating place.

The semi-artificial turf sheet structure is essentially required only toinclude the artificial turf portion and the natural turf portion, andthe plant growth sheet structures of the type 2 already described andthe natural turf sheet structures obtained therefrom may be employed asthe semi-artificial turf sheet structure or the semi-artificial turfsheet structure piece in this method. In this case, the plant protectionprojections at either of these structures can be used as the artificialturf portion, and the seeds held at the plant seed holding layer and thenatural turf growing therefrom can be used as the natural turf portion.

The semi-artificial turf sheet structure in this method may beselectively formed of the plant growth sheet structure of the aboveitems (α) and (β) as well as the natural turf sheet structures includingthe turf growing at these plant growth sheet structures.

In the method of laying the turf sheet structure according to theinvention, the semi-artificial turf sheet structure may be formed of aplurality of semi-artificial turf sheet structure pieces.

In any cases, the outdoor accommodating place may be an outer walland/or a roof of the large-scale facilities, and also may be an outerwall and/or a roof of a building neighboring to the large-scalefacilities.

According to the method of laying the turf sheet structure of theinvention, the turf sheet structure, which is formed of thesemi-artificial turf sheet structure including the artificial turfportion and the natural turf portion, is accommodated at the outdooraccommodating place outside the large-scale facilities for growing theturf. Therefore, the method does not require a warehouse foraccommodating and storing the turf sheet structure, and thesemi-artificial turf sheet structure can be easily accommodated at thelarge outdoor accomodating place while growing the natural turf portion.The semi-artificial turf sheet structure, in which the natural turfportion was damaged during use, can be restored by growing the naturalturf during accommodation and storage so that it can be used again,although this depends on a degree of damage.

Since the semi-artificial turf sheet structure is laid in the outdooraccommodating place, surroundings around the large-scale facilities canbe greened by locating the outdoor accommodating place around thelarge-scale facilities.

Since the semi-artificial turf sheet structure is laid and accommodatedat the outdoor accommodating place outside the large-scale facilities,the structure can be easily transferred to and laid in the large-scalefacilities.

In the case where the semi-artificial turf sheet structure is formed ofa plurality of semi-artificial turf sheet structure pieces, the turfsheet structure can be divided into pieces for laying and accommodatingthe same at the outdoor accommodating place, so that the structure canbe laid and accommodated in accordance with a configuration of aninstallation area of the outdoor accommodating place.

The transfer of the semi-artificial turf sheet structure between thelarge-scale facilities and the outdoor accommodating place can beperformed by transferring the divided pieces of the turf sheetstructure, so that the semi-artificial turf sheet structure can betransferred easily even if it has a large area as a whole.

In the case where the outdoor accommodating place is defined by theouter wall of the large-scale facilities such as a balcony at the outerwall, the floor of the balcony can be greened by covering it with thesemi-artificial turf sheet structure. Rainwater may be led to thebalcony through gutters or the like for supplying it to the turf sheetstructure. Alternatively, the balcony may be additionally provided witha water nozzle. In these manners, maintenance for growing the naturalturf portion at the turf sheet structure can be performed easily.

In the case where the outdoor accommodating place is defined by a roofof the large-scale facilities, the semi-artificial turf sheet structureof a large area can be accommodated easily, and, owing to rainfall tothe roof or water supplied from additionally provided water nozzles orthe like, maintenance for growing the natural turf portion at thesemi-artificial turf sheet structure can be performed easily.

In the case where the outdoor accommodating place is a place such as abalcony defined by the outer wall of the building neighboring to thelarge-scale facilities, maintenance for growing the natural turf portionat the semi-artificial turf sheet structure can be performed easily,similarly to the case of, e.g., the balcony defined by the outer wall ofthe large-scale facilities themselves.

In the case where the outdoor accommodating place is defined by a roofof the building neighboring to the large-scale facilities, thesemi-artificial turf sheet structure of a large area can be accommodatedeasily, and, owing to rainfall to the roof or water supplied fromadditionally provided water nozzles, maintenance for growing the naturalturf portion can be performed easily.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross section showing an example of a plant growthsheet structure according to the invention together with turf seedssowed therein;

FIG. 2 is a schematic cross section of a natural turf sheet structureobtained from the plant growth sheet structure shown in FIG. 1;

FIG. 3 is a schematic cross section showing another example of a plantgrowth sheet structure according to the invention;

FIG. 4 is a schematic cross section of a natural turf sheet structureobtained from the plant growth sheet structure shown in FIG. 3;

FIG. 5 is a schematic cross section of still another example of a plantgrowth sheet structure according to the invention;

FIG. 6 is a schematic cross section of a natural turf sheet structureobtained from the plant growth sheet structure shown in FIG. 5;

FIG. 7 is a cross section of a concrete dam for showing an example of amethod of growing a turf according to the invention;

FIG. 8 is a plan of the dam shown in FIG. 7;

FIG. 9 is a cross section of a semi-artificial turf sheet structurepiece shown in FIG. 8;

FIG. 10 is a cross section of a major portion of a concrete dam forshowing another example of a method of growing a turf according to theinvention;

FIG. 11 is a plan showing still another example of a method of growing aturf according to the invention, and specifically showing a retentionpond and its surrounding;

FIG. 12 is a cross section taken along line A-A in FIG. 11;

FIG. 13 is a cross section of a domed stadium for showing an example ofa method of laying a turf sheet structure of the invention;

FIG. 14 is a plan of the stadium in FIG. 13;

FIG. 15 is a cross section of a balcony portion of the domed stadium inFIG. 13;

FIG. 16 is a cross section of another example of a balcony portion ofthe domed stadium in FIG. 13; and

FIG. 17 shows a domed stadium and a neighboring building for showinganother example of laying the turf sheet structure of the invention.

PREFERRED EMBODIMENTS OF THE INVENTION

Embodiments of the invention will now be described below with referenceto the drawings.

FIG. 1 is a schematic cross section of an example A1 of a plant growthsheet structure according to the invention, and specifically shows astate that turf seeds are sowed. FIG. 2 is a schematic cross section ofan example B1 of a natural turf sheet structure according to theinvention. The natural turf sheet structure B1 shown in FIG. 2 is formedwhen the turf seeds grow at the plant growth sheet structure A1 shown inFIG. 1.

The plant growth sheet structure A1 shown in FIG. 1 includes a base weblayer 1 and a core layer 2 which are layered in this order along anascending direction, and is provided at a surface of the core layer 2with a large number of flexible plant protection projections 3.

The base web layer 1 is a cotton web layer which is used at the rate of300 g/m² and is formed of synthetic fiber cotton of 50% made ofpolyester fibers of 6 deniers and water-absorbing cotton of 50% made ofwater-absorbing acrylic fibers (Runseal F manufactured by Toyo BousekiCo. Ltd.).

The core layer 2 is a three-dimensional mesh structure formed ofentangled synthetic resin fibers, and is Zeomat 7020 manufactured byZeon Co., Ltd. in this embodiment. More specifically, the core layer 2is formed of entangled polyamide filaments of 0.5 mm in diameter, and isused at the rate of 420 g/m² and has a whole thickness of 20 mm. Thecore layer 2 has irregularities at its opposite surfaces, and alsointernally has continuous gaps, so that it has sufficient gas and waterpermeabilities. As a whole, it has a flexibility and an elasticity aswell as a form-maintaining property and an appropriate strength. Itallows easy loading of powder and particles such as sand.

Pile yarns 3A are woven through the core layer 2 into the base web layer1, so that the base web layer 1 and the core layer 2 are integrallycoupled to prevent decomposition.

The pile yarns 3A form a large number of loop piles 3 a which aresubstantially uniformly dispersed and are projected from the surface ofthe core layer 2. The loop piles 3 a form the flexible plant protectionprojections 3.

The pile yarn 3A is a polyamide bulky long fiber (generally called a“BCFnylon yarn”) of 3000d/39f (d: denier, f: filament), and is formed of amixture of green filaments and brown filaments so that it is coloredsimilarly to the color of a natural turf. The pile yarns 3A have a watertransferring property by a capillary phenomenon and are woven with{fraction (5/16)} inch gage and 4 stitches. A height of the pile (plantprotection projection) from the core layer 2 is about 5 mm to about 6mm.

In this embodiment, a backing member is not arranged under the base weblayer 1. However, if the piles 3 a are cut-piles, a backing member 4 isapplied to the lower surface of the base web layer 1 so as to preventdisengagement of the pile yarns 3A, as indicated by alternate long andtwo short dashes line. The backing member 4, if employed, may be formedby applying, in a thin form, a backing material having awater-nonsolubility and a gas permeability such as a mechanically foamedSBR latex, or by applying a water-soluble backing material such aspolyvinyl alcohol or vinyl acetate resin emulsion. If the water-solublebacking material is to be used, at least a portion of the material maycontain fertilizer.

The plant growth sheet structure A1 described above is formed from anelongated structure which was mass-produced in a factory. The elongatedstructure has a flexibility so that it can be rolled for storage andtransfer. When used, it is cut into an appropriate size.

The structure A1 cut into an appropriate size is laid, for example, at aground such as a general house garden, a park, a river bank, a golfcourse, a hillock or a seaside, at a planting zone of a building, roador the like, or at sport facilities. It may also be laid in a place orfacilities dedicated to growth of the natural turf sheet structure B1from the structure A1. This laying operation can be performed relativelyeasily. Also, the laid structure can be transferred.

Seeds such as turf seeds 5 are sowed in the plant growth sheet structureA1 laid in an intended place. The sowed turf seeds 5 are located betweenthe plant protection projections 3 or in the core layer 2. In thisstate, water containing or not containing plant growing nutrient issupplied to the structure A1 under an appropriate temperature condition,so that the base web layer 1 absorbs and retains the water. Thereby, theturf seeds 5 germinate and grow into a turf 6 as shown in FIG. 2. Atthis stage, the structure A1 forms the natural turf sheet structure B1.The natural turf sheet structure B1 is also supplied with water with orwithout turf growing nutrient, which is absorbed into and retained atthe base web layer 1. Thereby, the turf is maintained and grows.

Roots 61 of grown turf 6 reach base web layer 1, and are suppliedtherefrom with water with or without nutrient in solution.

The pile yarns 3A, which have water retaining and transferringproperties and are woven through the core layer 2 into the base weblayer 1, absorb water with or without nutrient. They also retain waterwith or without nutrient which is supplied from a higher position.

Even in a structure including the backing member 4, in the case wherethe member 4 is arranged to allow water flow between the base web layer1 and the lower exterior, the base web layer 1 can absorb water in soilor the like over which the base web layer 1 is laid, and can alsodischarge surplus water into soil or the like. In the structure wherethe backing member 4 is made of a water-soluble material which partiallyor entirely contains fertilizer, the backing member is dissolved tosupply nutrient in accordance with use of the structure. If the member 4has a portion containing fertilizer, it is not essential to mix water tobe supplied with nutrient, and external supply of nutrient can beeliminated.

If a plurality of structures each having an appropriate size andcorresponding to either of the above structures, i.e., the plant growthsheet structure A1 or the natural turf sheet structure B1, are to bearranged, the adjacent structures can be integrally coupled, e.g., bymachine-sewing portions of the base web layers 1, if necessary. Thisintegration improves the installation stability, which is preferred insport facilities or the like.

If a plurality of structures of an appropriate size are arranged incontact with each other, the base web layers 1 function as waterpassages to supply water with or without nutrient uniformly to the wholestructures, even if the water with or without nutrient is supplied toonly a portion of the whole structures.

In the plant growth sheet structure A1, the sewed turf seeds 5, whichare located between the plant protection projections 3 at the surface ofthe core layer 2 or are located in the core layer 2, are substantiallyprevented from moving therefrom and are stably held at the samepositions. Therefore, sprouts and roots growing from the seeds are heldsubstantially stably at the same positions, and are prevented from beingmoved and flowed by the wind, rain, irrigated water and others. In thenatural turf sheet structure B1, since the turf roots 61 extend betweenthe plant protection projections 3 and, in many cases, into the corelayer 2, the turf is prevented from being moved and flowed by the wind,rain, irrigated water and others. Accordingly, the plant growth sheetstructure A1 is suitable to growth of plants at an inclined surfacewhich is often washed with rainwater or irrigated water, a seasideexposed to a strong wind or places near these places. Also, the naturalturf sheet structure B1 is suitable to maintenance and growth of naturalturfs at an inclined surface which is often washed with rainwater orirrigated water, a seaside exposed to a strong wind or places near theseplaces. In view of these points, maintenance of growing and grown turfscan be performed easily.

In either of the plant growth sheet structure A1 and the natural turfsheet structure B1, the pile yarn 3A is woven through the core layer 2into the base web layer 1 for integrating the whole structure, so thatthe structure is sufficiently suppressed from being decomposed by anexternal force. Since the core layer 2 is provided at the surface withthe plant protection projections 3, the protection projections 3 in theplant growth sheet structure A1 protect the sowed turf seeds 5, sprouts,roots 61 and others against a downward load, a lateral pulling load orthe like. Also, the protection projections 3 in the natural sheetstructure B1 protect the sprouts, roots 61 and others against a downwardload, a lateral pulling load or the like. In this manner, damage bythese loads is suppressed. Since the decomposition is suppressed and theprotection projections 3 protect the turf roots and others, thestructure can be used in sport facilities although this depends on thekinds of sports. Owing to the foregoing, the growth and maintenance ofthe turf can be performed easily.

The pile yarns 3A are colored similarly to the turf, and thus the plantprotection projections 3 at the surface of the structure are similarlycolored. Therefore, the plant growth sheet structure A1 does not exhibitan unpreferable appearance even before growth of the turf 6 from thesowed seeds 5, and even when the grown turf 6 is partially damaged orlost due to shaving, withering or the like. Also, the natural turf sheetstructure B1 does not exhibit an unpreferable appearance even when theturf 6 is partially damaged or lost due to shaving, withering or thelike, because the protection projections 3 colored similarly to thesurrounding turf 6 appear at the damaged area.

In either of the plant growth sheet structure A1 and the natural turfsheet structure B1, the base web layer 1 which has increased its weightowing to retention of water and other portions can press possible seedsof weeds at an installation place, so that growth of the weeds issuppressed, and a time-consuming work for removing the weeds can beeliminated, which also facilitates growth and maintenance of the turf.

In either of the plant growth sheet structure A1 and the natural turfsheet structure B1, the base web layer 1 can absorb and retain the watersupplied thereto, and also can be compressed to discharge the water, sothat the quantity of retained water can be controlled easily. By thiscontrol of retained water, supply of water with or without nutrient canbe controlled easily, so that the growth and maintenance of the turf canbe performed easily.

Since the weight of the base web layer 1 can be controlled bycontrolling the quantity of retained water, this weight control can beperformed for reducing the whole weight of the structure A1 or B1 sothat the structure may be transferred easily. Alternatively, the weightcan be increased to improve the installation stability of the structureat the installation place, so that the structure can achieve asufficient installation stability even when it is installed at a place,e.g., in sport facilities where the structure receives a severe forcefrom a player, although this depends on the kinds of sports.

FIG. 3 is a schematic cross section of another example A2 of a plantgrowth sheet structure according to the invention, and specificallyshows a state in which turf seeds are held at the structure. FIG. 4 is aschematic cross section of another example B2 of a natural turf sheetstructure according to the invention. The natural turf sheet structureB2 shown in FIG. 4 corresponds to the plant growth sheet structure A2shown in FIG. 3 in which the turf seeds have germinated and grown.

The plant growth sheet structure A2 shown in FIG. 3 includes the baseweb layer 1, a plant seed holding layer 5A and the core layer 2, whichare layered in this order along an ascending direction and areintegrally coupled. The core layer 2 is provided at its surface with alarge number of flexible protection projections 3.

The structure A2 is the same as the plant growth sheet structure A1shown in FIG. 1 except for that the plant seed holding layer 5A ispinched between the base web layer 1 and the core layer 2. The sameparts and portions as those in the structure A1 bear the same referencenumbers.

The plant seed holding layer 5A includes a flexible thin non-wovenfabric sheet 52 having a gas permeability on which the turf seeds 5 areuniformly dispersed, and a flexible turf seed retaining film 51 having awater-solubility and mainly made of a protein material is laminated overthe sheet 52, so that germination of the turf seeds and subsequentgrowth are not impeded. The turf seeds 5 in this embodiment may be seedsof turf and also may be runners or the like obtained from cut turfs.

The pile yarns 3A are woven through the core layer 2 into the base weblayer 1, so that the base web layer 1, plant seed holding layer 5A andcore layer 2 are integrally coupled to prevent decomposition.

The pile yarns 3A form a large number of loop piles 3 a which aresubstantially uniformly dispersed and projected from the surface of thecore layer 2, so that the loop piles 3 a form the flexible plantprotection projections 3.

In this embodiment, a backing member is not arranged under the base weblayer 1. However, if the piles 3 a are cut-piles, the backing member 4is applied to the lower surface of the base web layer 1 so as to preventdisengagement of the pile yarns 3A, as indicated by alternate long andtwo short dashes line in FIGS. 3 and 4. The specific substance andothers of the backing member 4 may be the same as those of the backingmember 4 already described in connection with the plant growth sheetstructure A1.

The plant growth sheet structure A2 described above is formed from anelongated structure which was mass-produced in a factory. The elongatedstructure has a flexibility so that it can be rolled for storage andtransfer. When used, it is cut into an appropriate size.

The structure A2 cut into an appropriate size is laid, for example, at aground such as a general house garden, a park, a river bank, a golfcourse, a hillock or a seaside, at a planting zone of a building, roador the like, or at sport facilities. It may also be laid in a place orfacilities dedicated to growth of the natural turf sheet structure B2from the structure A2. This laying operation can be performed easily.Also, the laid structure can be transferred.

The plant growth sheet structure A2 laid in a predetermined place issupplied with water containing or not containing turf growing nutrient.The base web layer 1 absorbs and retains the water, so that the turfseeds 5 germinate and grow into the natural turf 6 as shown in FIG. 4.At this stage, the structure A2 forms the natural turf sheet structureB2. The natural turf sheet structure B2 is supplied with watercontaining or not containing turf growing nutrient, and the base weblayer 1 absorbs and retains the water, so that the turf is maintainedand newly grows.

The roots 61 of grown turf 6 extend to the base web layer 1 through theresidual non-woven fabric sheet 52 in the plant seed holding layer 5A,so that they are supplied therefrom with water containing or notcontaining nutrient.

The pile yarns 3A, which have water retaining and transferringproperties and are woven through the core layer 2 into the base weblayer 1, absorb water with or without nutrient from the base web layer1. They also retain water with or without nutrient which is suppliedfrom a higher position.

Even in a structure including the backing member 4, in the case wherethe member 4 is arranged to allow water flow between the base web layer1 and the lower exterior, the base web layer 1 can absorb water in soilor the like over which the layer 1 is laid, and can also dischargesurplus water into soil or the like. In the structure where the backingmember 4 is made of a water-soluble material which partially or entirelycontains fertilizer, the backing member is dissolved to supply nutrientin accordance with use of the structure. If the member 4 has a portioncontaining fertilizer, it is not essential to mix water to be suppliedwith nutrient, and external supply of nutrient can be eliminated.

If a plurality of structures each having an appropriate size andcorresponding to either of the above structures, i.e., the plant growthsheet structure A2 or the natural turf sheet structure B2, are to bearranged, the adjacent structures can be integrally coupled, e.g., bymachine-sewing portions of the base web layers 1 or providing a planarfastener, if necessary. This integration improves the installationstability, which is preferred, e.g., in sport facilities.

If a plurality of structures of an appropriate size are arranged incontact with each other, the base web layers 1 function as waterpassages to supply water with or without nutrient uniformly to the wholestructures, even if the water with or without nutrient is supplied toonly a portion of the whole structures.

In the plant growth sheet structure A2, since the turf seeds 5 arelocated between the base web layer 1 and the core layer 2 which isprovided at its surface with the plant protection projections 3, theturf seeds 5 are substantially prevented from moving therefrom and arestably held at the same positions, and sprouts and roots growing fromthe seeds are held substantially stably at the same positions, and areprevented from being moved and flowed by the wind, rain, irrigated waterand others. In the natural turf sheet structure B2, since the turf roots61 extend into the core layer 2 and the base web layer 1, and, in somecases, between the plant protection projections 3, the turf is preventedfrom being moved and flowed by the wind, rain, irrigated water andothers. Accordingly, the plant growth sheet structure A2 is suitable togrowth of plants at an inclined surface which is often washed withrainwater or irrigated water, a seaside exposed to a strong wind orplaces near these places. Also, the natural turf sheet structure B2 issuitable to maintenance and growth of natural turfs at an inclinedsurface which is often washed with rainwater or irrigated water, aseaside exposed to a strong wind or places near these places. In view ofthese points, maintenance of growing and grown turfs can be performedeasily.

Either of the plant growth sheet structure A2 and the natural turf sheetstructure B2 has an entirely integrated structure, so that the structureis sufficiently suppressed from being decomposed by an external force.Since the core layer 2 is provided at the surface with the plantprotection projections 3, the core layer 2 and the protectionprojections 3 in the plant growth sheet structure A2 protect the turfseeds 5 at the plant seed holding layer 5A as well as sprouts, roots andothers growing therefrom against a downward load, a lateral pulling loador the like. Also, in the natural turf sheet structure B2, the sprouts,roots 61 and others of the turf 6 are protected by the core layer 2 andthe projections 3 against a downward load, a lateral pulling load or thelike. Therefore, the structure can be used in sport facilities althoughthis depends on the kinds of sports. Owing to the foregoing, the growthand maintenance of the turf can be performed easily.

The pile yarns 3A are colored similarly to the turf, and thus the plantprotection projections 3 at the surface of the structure are similarlycolored. Therefore, the plant growth sheet structure A2 does not exhibitan unpreferable appearance even before growth of the turf 6 from theheld seeds 5, and even when the grown turf 6 is partially damaged orlost due to shaving, withering or the like. Also, the natural turf sheetstructure B2 does not exhibit an unpreferable appearance even when theturf 6 is partially damaged or lost due to shaving, withering or thelike, because the protection projections 3 colored similarly to thesurrounding turf 6 appear at the damaged area.

In either of the plant growth sheet structure A2 and the natural turfsheet structure B2, the base web layer 1 which has increased its weightowing to retention of water and other portions can press possible seedsof weeds at an installation place, so that growth of the weeds issuppressed, and a time-consuming work for removing the weeds can beeliminated, which also facilitates growth and maintenance of the turf.

In either of the plant growth sheet structure A2 and the natural turfsheet structure B2, the base web layer 1 can absorb and retain the watersupplied thereto, and also can be compressed to discharge the water, sothat the quantity of retained water can be controlled easily. By thiscontrol of retained water, supply of water with or without nutrient canbe controlled easily, so that the growth and maintenance of the turf canbe performed easily.

Since the weight of the base web layer 1 can be controlled bycontrolling the quantity of retained water, this weight control can beperformed for reducing the whole weight of the structure A2 or B2, sothat the structure may be moved easily. Alternatively, the weight can beincreased to improve the installation stability of the structure at theinstallation place, so that the structure can achieve a sufficientinstallation stability even when it is installed at a place, e.g., insport facilities where the structure receives a severe force from aplayer, although this depends on the kinds of sports.

FIG. 5 is a schematic cross section of still another example A3 of aplant growth sheet structure according to the invention, andspecifically shows a state in which turf seeds are held at thestructure. FIG. 6 is a schematic cross section of still another exampleB3 of a natural turf sheet structure according to the invention. Thenatural turf sheet structure B3 shown in FIG. 6 corresponds to the plantgrowth sheet structure A3 shown in FIG. 5 in which the turf seeds havegerminated and grown.

As shown in FIG. 5, the plant growth sheet structure A3 includes thebase web layer 1, core layer 2 and plant seed holding layer 5A as wellas a cover web layer 7 which are layered in this order along anascending direction. The pile yarns 3A are woven through the cover weblayer 7 into the base web layer 1, and a large number of flexible plantprotection projections 3 which are uniformly dispersed and are projectedfrom the surface of the cover web layer 7.

The structure A3 is similar to the plant growth sheet structure A2already described except for that the cover web layer 7 is arranged overthe core layer 2, and the plant seed holding layer 5A is pinched betweenthe cover web layer 7 and the core layer 2. The same or similar partsand portions as those in the structure A2 bear the same referencenumbers.

The base web layer 1 is a cotton web layer which is used at the rate of300 g/m² and is formed of synthetic fiber cotton of 50% made ofpolyester fibers of 6 deniers and water-absorbing cotton of 50% made ofwater-absorbing acrylic fibers (Runseal F manufactured by Toyo BousekiCo. Ltd.). The cover web layer 7 is a cotton web layer which is used atthe rate of 100 g/m² and is formed of a mixture of 50% synthetic fibercotton and 50% water-absorbing cotton, similarly to the web layer 1.

The cotton web layers 1 and 7, between which the core layer 2 and theplant seed holding layer 5A are pinched, are mutually coupled by theneedle punch method and specifically by needling with 50 times persquare centimeter. Cotton fibers forming the web layers 1 and 7 arepartially entangled through the core layer 2 and the plant seed holdinglayer 5A to couple them integrally.

The core layer 2 is a Zeomat 7020 manufactured by Zeon co., Ltd., and isthe same as those of the core layers 2 in the plant growth sheetstructures A1 and A2 already described. It is used at the rate of 420g/cm² and has a whole thickness of 20 mm.

The plant seed holding layer 5A is the same as the plant seed holdinglayer 5A in the plant growth sheet structure A2 already described, andincludes the non-woven fabric sheet 52 on which the turf seeds 5 areuniformly dispersed. The turf seed retaining film 51 is laminated overthe sheet 52, so that germination of the turf seeds and subsequentgrowth are not impeded. The turf seeds 5 in this embodiment may be seedsof turf and also may be runners or the like obtained from cut turfs.

The pile yarn 3A has the same structure and substance as the pile yarns3A in the plant growth sheet structures A1 and A2, and is a polyamidebulky long fiber (generally called a “BCF nylon yarn”) of 3000d/39f (d:denier, f: filament). The pile yarns 3A are colored green, and are wovenwith {fraction (5/16)} inch gage and 4 stitches. The pile yarns 3A thuswoven form the loop piles 3 a at the surface of the cover web layer 7,and the loop piles 3 a form the flexible plant protection projections 3.A height of the pile (plant protection projection) formed at the surfaceof the cover web layer 7 is about 5 mm to about 6 mm. The pile yarn 3Amay be colored similarly to that in the structure A2 by employingmixture of green filaments and brown filaments.

The pile yarns 3A thus woven and the cotton fibers connecting the weblayers 1 and 7 together achieve the integral coupling which has asufficient resistance against decomposition of the whole structure.

This embodiment does not include a backing member under the base weblayer 1. However, if the piles 3 a are cut-piles, the backing member 4is applied to the lower surface of the base web layer 1 so as to preventdisengagement of the pile yarns 3A, as indicated in FIGS. 5 and 6 byalternate long and two short dashes line. The backing member 4, ifemployed, may be the same as that already described in connection withthe plant growth sheet structure A1.

The plant growth sheet structure A3 described above is formed from anelongated structure which was mass-produced in a factory. The elongatedstructure has a flexibility so that it can be rolled for storage andtransfer. When used, it is cut into an appropriate size.

The structure A3 cut into an appropriate size is laid, for example, at aground such as a general house garden, a park, a river bank, a golfcourse, a hillock or a seaside, at a planting zone of a. building, roador the like, or at sport facilities. It may also be laid in a place orfacilities dedicated to growth of the natural turf sheet structure B3from the structure A3. This laying operation can be performed relativelyeasily. Also, the laid structure can be transferred.

The plant growth sheet structure A3 laid in a predetermined place issupplied with water containing or not containing plant growing nutrient,so that the base web layer 1 and cover web lay 7 absorb and retain thewater. Thereby, the turf seeds 5 germinate and grow into a turf 6 asshown in FIG. 6. At this stage, the structure A3 forms the natural turfsheet structure B3. The natural turf sheet structure B3 is also suppliedwith water with or without turf growing nutrient, which is absorbed intoand retained at the base web layer 1 and the cover web layer 7. Thereby,the turf is maintained and grows.

Roots 61 of grown turf 6 reach base web layer 1 through the residualnon-woven fabric sheet 52 in the plant seed holding layer 5A and thecore layer 2, and are supplied therefrom with water containing or notcontaining nutrient in solution.

The pile yarns 3A, which have water retaining and transferringproperties and are woven through the cover web layer 7 into the base weblayer 1, absorb water with or without nutrient from the base web layer1. They also retain water with or without nutrient which is suppliedfrom a higher position.

Even in a structure including the backing member 4, in the case wherethe member 4 is arranged to allow water flow between the base web layer1 and the lower exterior, the base web layer 1 can absorb water in soilor the like over which the layer 1 is laid, and can also dischargesurplus water into soil or the like. In the structure where the backingmember 4 is made of a water-soluble material which partially or entirelycontains fertilizer, the backing member is dissolved to supply nutrientin accordance with use of the structure. If the member 4 has a portioncontaining fertilizer, it is not essential to mix water to be suppliedwith nutrient, and external supply of nutrient can be eliminated.

If a plurality of structures each having an appropriate size andcorresponding to either of the above structures, i.e., the plant growthsheet structure A3 or the natural turf sheet structure B3, are to bearranged, the adjacent structures can be integrally coupled, e.g., bymachine-sewing portions of the base web layers 1 or providing a planarfastener, if necessary. This integration improves the installationstability, which is preferred, e.g., in sport facilities.

If a plurality of structures of an appropriate size are arranged incontact with each other, the base web layers 1 function as waterpassages to supply water with or without nutrient uniformly to the wholestructures, even if the water with or without nutrient is supplied toonly a portion of the whole structures.

In the plant growth sheet structure A3, since the turf seeds 5 are heldat the plant seed holding layer 5 and are located between the core layer2 and the cover web layer 7, the turf seeds 5 are substantiallyprevented from moving therefrom and are stably held at the samepositions. Therefore, sprouts and roots growing from the seeds are heldsubstantially stably at the same positions, and are prevented from beingmoved and flowed by the wind, rain, irrigated water and others. In thenatural turf sheet structure B3, since the turf roots 61 extend into thecore layer 2 and the base web layer 1, the turf is prevented from beingmoved and flowed by the wind, rain, irrigated water and others.Accordingly, the plant growth sheet structure A3 is suitable to growthof plants at an inclined surface which is often washed with rainwater orirrigated water, a seaside exposed to a strong wind or places near theseplaces. Also, the natural turf sheet structure B3 is suitable tomaintenance and growth of natural turfs at an inclined surface which isoften washed with rainwater or irrigated water, a seaside exposed to astrong wind or places near these places. In view of these points,maintenance of growing and grown turfs can be performed easily.

Either of the plant growth sheet structure A3 and the natural turf sheetstructure B3 has an entirely integrated structure, so that the structureis sufficiently suppressed from being decomposed by an external force.Since the cover web layer 7 is employed, and is provided at the surfacewith the plant protection projections 3, the cover web layer 7 and theprotection projections 3 in the plant growth sheet structure A3 protectthe turf seeds 5 at the plant seed holding layer 5A as well as sprouts,roots and others growing therefrom against a downward load, a lateralpulling load or the like. Also, in the natural turf sheet structure B3,the sprouts, roots 61 and others of the turf 6 are protected by thecover web layer 7 and the plant protection projections 3 against adownward load, a lateral pulling load or the like. Therefore, thestructure can be used in sport facilities although this depends on thekinds of sports. Owing to the foregoing, the growth and maintenance ofthe turf can be performed easily.

The pile yarns 3A are colored similarly to the turf, and thus the plantprotection projections 3 at the surface of the structure are similarlycolored. Therefore, the plant growth sheet structure A3 does not exhibitan unpreferable appearance even before growth of the turf 6 from theheld seeds 5, and even when the grown turf 6 is partially damaged orlost due to shaving, withering or the like. Also, the natural turf sheetstructure B3 does not exhibit an unpreferable appearance even when theturf 6 is partially damaged or lost due to shaving, withering or thelike, because the protection projections 3 colored similarly to thesurrounding turf 6 appear at the damaged area.

In either of the plant growth sheet structure A3 and the natural turfsheet structure B3, the base web layer 1 which has increased its weightowing to retention of water and other portions can press possible seedsof weeds at an installation place, so that growth of the weeds issuppressed, and a time-consuming work for removing the weeds can beeliminated, which also facilitates growth and maintenance of the turf.

In either of the plant growth sheet structure A3 and the natural turfsheet structure B3, the base web layer 1 can absorb and retain the watersupplied thereto, and also can be compressed to discharge the water, sothat the quantity of retained water can be controlled easily. By thiscontrol of retained water, supply of water with or without nutrient canbe controlled easily, so that the growth and maintenance of the turf canbe performed easily.

Since the weight of the base web layer 1 can be controlled bycontrolling the quantity of retained water, this weight control can beperformed for reducing the whole weight of the structure A3 or B3, sothat the structure may be moved easily. Alternatively, the weight can beincreased to improve the installation stability of the structure at theinstallation place, so that the structure can achieve a sufficientinstallation stability even when it is installed at a place, e.g., insport facilities where the structure receives a severe force from aplayer, although this depends on the kinds of sports.

Then, an embodiment of a method of growing a turf according to theinvention will be described below.

First, the embodiment of the method of growing the turf will bedescribed below with reference to FIGS. 7 through 9. In this embodiment,a natural turf is grown at a wall surface of a concrete dam 10 with asemi-artificial turf sheet structure 20 (will be referred to as a“semi-artificial turf 20” hereafter).

The semi-artificial turf 20 is laid over each of an inclined wallsurface 30 at rear side for storing water, a vertical wall surface 40projecting vertically from an upper edge of the inclined wall surface30, a horizontal wall surface 50 which extends perpendicularly from anupper edge of the vertical wall surface 40 and forms a top of theconcrete dam 10, and a front wall surface 60 at the front side of theconcrete dam 10.

The semi-artificial turf 20 is formed of a plurality of semi-artificialturf sheet structure pieces 70 (which will be referred to as“semi-artificial turf pieces” hereafter), as shown in FIG. 8, which arearranged over the walls surfaces 30, 40 and 50 without any gap, and arejoined together. The front wall surface 60 is also covered, except for awater discharge port and its lower portion, with the semi-artificialturf 20 formed of the semi-artificial turf pieces 70 joined together.

The semi-artificial turf piece 70 forming the semi-artificial turf 20 isformed of a sheet portion 80, artificial turf portions 90 arranged atthe sheet portion 80 and natural turf portions 100, as shown in FIG. 9.The sheet portion 80 is formed of a seed sheet 80 a having seeds of anatural turf, and a pair of upper and lower surface sheets 80 b locatedat opposite sides of the seed sheet 80 a. The surface sheet 80 b isformed of synthetic fiber cotton containing water-absorbing fibers.

The natural turf portion 100 is formed of a turf growing from the seedsheet 80 a, and has a height larger than the artificial turf portion 90.The artificial turf portion 90 is formed of the foregoing BCF nylon(more specifically BCF nylon 6), has a loop form and is fixed to one ofthe surface sheets 80 b by urethane adhesive. The surface of theartificial turf portion 90 is covered with the natural turf portion 100.

Accordingly, in the semi-artificial turf piece 70, the loop structuresof the artificial turf portion 90 hidden in the natural turf portion 100form an elastic support member, which prevents falling or tumbling ofthe natural turf portion 100 and provides an appropriate cushioningproperty. Even when the natural turf portion 100 is damaged, a newnatural turf will appear from a lower side when it grows to some extent,so that the natural turf portion 100 will be naturally restored. Evenimmediately after the natural turf portion 100 is damaged, theartificial turf portion 90 appears to compensate the damaged appearance.

The natural turf portions 100 of the semi-artificial turfs 20 laid overthe wall surfaces 30, 40, 50 and 60 of the concrete dam 10 are grown asfollows:

As shown in FIG. 8, a piping 11 for water supply is arranged at the wallsurfaces 30, 40, 50 and 60, and opposite ends of the piping 10 aredisposed in a reservoir 12 behind the concrete dam 1. The piping 11 isprovided with a pump (not shown), which circulates water in thereservoir 12 through the piping 11.

The piping 11 is provided with a plurality of faucets 13, which supplywater to the semi-artificial turfs 20, and also supply nutrient such asnitrogen, phosphoric acid and potassium, so that hydroponic culturing ofthe natural turf portions 100 of the semi-artificial turfs 20 isperformed.

The nutrient for growing the natural turf portion is directly suppliedin an appropriate manner or is mixed into the water to be supplied.

In this manner, the semi-artificial turfs 20 are laid over the wallsurfaces 30, 40, 50 and 60 of the concrete dam 10 for growing the same,whereby the concrete wall surfaces 30, 40, 50 and 60 are covered withthe semi-artificial turfs 20 and are not exposed to the direct sunshine,wind and rain, so that it is possible to prevent deterioration of thewall surfaces 30, 40, 50 and 60. Since the wall surfaces 30, 40, 50 and60 are covered with the green semi-artificial turfs 20, the concretewalls can be greened easily.

Since the semi-artificial turfs 20 are laid over the wall surfaces 30,40, 50 and 60 of the concrete dam 10 for growing the same, water storedin the dam can be supplied together with nutrient through the piping 11and faucets 13 to the semi-artificial turfs 20, so that growth of thenatural turf portions 100 can be performed easily.

FIG. 10 shows an example, in which water is supplied to thesemi-artificial turf 20 laid over the inclined wall surface 30 of theconcrete dam 10, and, for this purpose, there is provided a runner ormobile unit 15 which runs on the inclined wall surface 30 and storeswater for supplying the water. The runner 15 is, for example, aradio-controlled mobile runner 15 which can move longitudinally andlaterally. The runner 15 is supported through a wire 16 by the verticalwall surface 40 to prevent falling from the inclined wall surface 30.The wire 16 is supplied from an unillustrated pulley, and is deliveredfrom or reeled up to the pulley in synchronization with downward orupward movement of the runner 15 along the inclined wall surface 30.

Then, another embodiment of a method of growing a turf according to theinvention will be described below with reference to FIGS. 11 and 12.

In this embodiment, the semi-artificial turfs 20 are grown at a concretewall surface 21 of a retention pond 20A.

The retention pond 20A, which is provided for temporarily and partiallystoring flood for lowering a flood level at a downstream position, issurrounded by a bank 22 made of, e.g., concrete. The concrete wall orsurface 21 is a surface of the bank 22, and the semi-artificial turf 20is laid over the wall surface 21 for growing the same. In FIG. 11, areference number 23 indicates an overflow bank provided at a portion ofthe bank 22, and a reference number 24 indicates a drain gate.

The semi-artificial turf 20 is grown at the concrete wall surface 21 ina manner similar to that for growing the semi-artificial turf sheetstructure at the concrete dam. More specifically, a water supply pipingis arranged at the wall surface 21, and water and nutrient are suppliedfrom faucets provided at the piping, or a sprinkler vehicle isperiodically used to supply water to them.

In this manner, the semi-artificial turf 20 is laid over the concretewall surface 21 of the retention pond 20A. For growing the turf, waterstored in the retention pond 20A is supplied together with nutrient tothe semi-artificial turf 20, so that the natural turf portion 100 of thestructure 20 can be grown easily.

If the retention pond 20A and its surroundings are used as a place forrecreation, they provide a comfortable place, because the concrete wallsurface 21, i.e., the top and opposite side surfaces of the bank 22 arecovered with semi-artificial turf 20.

In the method of growing the turf described above, the semi-artificialturf 20 is laid over each of the concrete wall surfaces 30, 40, 50 and60 of the concrete dam 10 or the concrete wall surface 21 of theretention pond 20A for performing hydroponics. However, the method isnot restricted to this, and may be employed for laying the turf over anouter wall (e.g., a balcony or a roof) of a general building forhydroponics.

Then, a method of laying a turf sheet structure according to theinvention will be described below with reference to FIGS. 13 to 17. Inthe embodiment described below, the turf sheet structure is formed of asemi-artificial turf sheet structure which is the substantially same asthe semi-artificial turf sheet structure 20 employed in the method ofgrowing the turf at the concrete wall described before. The turf sheetstructure in this embodiment is arranged at large-scale facilities, andmore specifically at a so-called domed stadium for a baseball, a socceror the like.

As shown in FIGS. 13 and 14, a domed stadium 10D is formed of asubstantially cylindrical outer wall 200 and a domed roof 300 arrangedat the top of the outer wall 200.

The outer wall 200 of the domed stadium is provided with a plurality ofbalconies (outdoor accommodating places) 400 arranged in acircumferential direction. The balconies 400 have annular forms and arearranged at vertically spaced three levels. These balconies 400accommodate semi-artificial turf sheet structures 500 which are to belaid in the domed stadium and each of them is formed of a plurality ofsemi-artificial turf sheet structure pieces 600.

The semi-artificial turf sheet structure piece 600 (which will bereferred to as the “semi-artificial turf piece 600” hereafter) is thesame as the semi-artificial turf sheet structure piece 70 shown in FIG.9, and has a width of about 1 m and a length of about 20 m.

The semi-artificial turf pieces 600 are circularly arranged at thebalcony 400. Water is supplied from a plurality of nozzles 101 to thesesemi-artificial turf pieces 600 as shown in FIG. 15. The nozzles 101 arearranged at the outer wall 200 with a circumferential space between eachother, and are connected to a water supply pipe (not shown).

The water supplied to the pipe may be service-water or may be rainwaterreceived on the roof 300 of the domed stadium 10D and stored in a tankthrough gutters, pipings or the like for supplying it, e.g., by a pump.

In this example, a game such as a baseball is not being played at thedomed stadium 10D, and it is not necessary to lay the semi-artificialturf sheet structures 500 (which will be referred to as the“semi-artificial turfs 500” hereafter) at the stadium 10D. In this case,a large number of semi-artificial turf pieces 600 forming thesemi-artificial turfs 500 are laid at the balconies 400 for storingthem, and the natural turfs 601 (see FIG. 15) of the semi-artificialturf piece 600 are grown by hydroponics. This growth is performed in thefollowing manner. Since the balconies 400 are located outdoors, thesemi-artificial turf pieces 600 are exposed to natural light as well asnatural rainwater and water periodically supplied from nozzles 101.Thereby, water-absorbing surface sheets (which are not shown butcorrespond to the surface sheet 80 b in the semi-artificial turf sheetstructure piece 70 shown in FIG. 9) sufficiently retain the water, bywhich the natural turf portions 601 are grown. The fertilizer (nitrogen,phosphoric acid and potassium) for the natural turf portion isappropriately supplied, or is mixed into the water to be supplied asdescribed above. When semi-artificial turfs 500 are to be laid in thedomed stadium 10D, the semi-artificial turf pieces 600 laid in thebalconies 400 are transferred to and laid in the domed stadium 10D. Inthis case, each semi-artificial turf piece 600 is rolled at the balcony400, and is transferred to an outside of the first floor of the domedstadium 10D, e.g., by a crane. These rolled pieces 600 are successivelytransferred through the entrance at the first floor. The semi-artificialturf pieces 600 thus transferred are then developed and joined togetherfor laying them in the domed stadium 10D.

When the semi-artificial turfs 500 arranged in the domed stadium 10D arenot required any longer, the semi-artificial turf pieces 600 forming theturfs 500 are rolled and removed from the floor. The semi-artificialturf pieces 600 thus rolled are successively transferred to the outsideof the domed stadium, and are transferred to the balconies 400, e.g., bya crane. These pieces 600 are successively developed and laid in thebalconies 400 for storing them, and the natural turf portions 601 of thesemi-artificial turf pieces 600 are grown at the balconies 400 similarlyto the foregoing manner.

By employing this manner of laying the semi-artificial turf 500 in thedomed stadium 10D, a warehouse for storing the turf sheet structures isnot required, and the semi-artificial turf 500 can be easily stored atthe large balconies while growing the natural turf portion. Since thesemi-artificial turf pieces 600 forming the semi-artificial turf 500 arelaid in the balconies 400, the balconies 400 can be greened.

Since the semi-artificial turf 500 is formed of a large number ofsemi-artificial turf pieces 600, the semi-artificial turf 500 can bestored in a divided and laid manner. Thus, the semi-artificial turfpieces 600 can be laid and stored circularly along the balconies, andtransfer of the semi-artificial turf 500 between the interior of thedomed stadium 10D and the balconies 400 can be performed easily.

FIG. 16 shows a modification of the balcony 400 for laying and storingthe semi-artificial turf pieces 600. At the bottom surface of thebalcony 400, there is arranged a conveyer system 11C for moving thesemi-artificial turf pieces 600 in the circumferential direction of thedomed stadium 10D.

The conveyer system 11C is formed of a large number of rollers 12Rarranged at the bottom surface of the balcony 400, an annularcirculating band 13B carried by the rollers 12R for movement in thecircumferential direction of the domed stadium 10D, and a drive motor Mwhich is engaged with a flange 13F formed at the outer periphery of thecirculating band 13B for circulating the band 13B in the circumferentialdirection of the domed stadium 10D. The semi-artificial turf pieces 600are laid and stored on the circulating band 13B.

The semi-artificial turf pieces 600 laid on the circulating band 13B aremoved in the circumferential direction of the domed stadium 10D inaccordance with circulation of the circulating band 13B.

As described above, the conveyer system 11C for moving thesemi-artificial turf pieces 600 in the circumferential direction of thedomed stadium is arranged at the balcony 400. In the operation ofgrowing the natural turf portions of the semi-artificial turf pieces 600at the balcony 400, therefore, the semi-artificial turf pieces 600 areappropriately circulated to expose them uniformly to the sunshine, sothat the natural turf portions can be grown efficiently. Also in theoperation of transferring the semi-artificial turf pieces 600 to andfrom the balcony 400, the semi-artificial turf pieces 600 can be moved,whereby the semi-artificial turf pieces 600 can be transferred throughone position to and from the balcony 400, and thus transfer of thesemi-artificial turf pieces 600 can be performed easily.

Then, description will be given on another embodiment of a method oflaying a turf sheet structure according to the invention with referenceto FIG. 17.

In this embodiment, a building (outdoor accommodating place) 20X builtnear the domed stadium 10D has a roof 21X, on which the semi-artificialturf pieces 600 are laid and stored. When the semi-artificial turf 500is to be laid in the domed stadium 10D, the semi-artificial turf pieces600 are rolled on the roof 21X of the building 20X. The rolledsemi-artificial turf pieces 600 are transferred to the outside of thefirst floor of the domed stadium, e.g., by a crane, and then the rolledsemi-artificial turf pieces 600 are successively transferred through theentrance at the first floor. The semi-artificial turf pieces 600 thustransferred are developed and joined together for laying them in thedomed stadium 10D.

As described above, the roof 21X of the building 20X near the domedstadium 10D is utilized as a place for accommodating and growing thesemi-artificial turf pieces 600. The building 20X does not have acircular plan shape but has a square plan shape in contrast to the domedstadium 10D. This achieves such an advantage that the semi-artificialturf pieces 600 can be easily arranged without a gap. Since thesemi-artificial turf pieces 600 are laid over the roof 21X, the roof 21Xis covered with the turf, so that the roof 21X can be effectively usedas a place for relaxation. In the case where the natural turf portionsof the semi-artificial turf pieces 600 are to be grown at the roof 21X,the growth can be performed similarly to the foregoing embodiment. Thus,the semi-artificial turf pieces 600 are exposed to the natural light.Also, the water can be supplied by rainfall, and the water andfertilizer can be periodically supplied, e.g., from sprinklers arrangedat the roof 21X.

In the foregoing embodiment, the semi-artificial turf pieces 600 areaccommodated at the balconies 400. Alternatively, the semi-artificialturf pieces 600 may be accommodated for growth at the roof 300 of thedomed stadium 10D or a garden for the semi-artificial turf pieces 600prepared radially outside the domed stadium 10D.

In the later embodiment, the semi-artificial turf pieces 600 areaccommodated for growth at the roof 21X of the building 20X.Alternatively, they may be accommodated for growth at another place suchas balconies of the building 20x.

INDUSTRIAL APPLICABILITY

The plant growth sheet structure and the natural turf sheet structure ofthe invention can be applied to a greening project for places to begreened, and a project for arranging the natural turf at places such asvarious sport facilities, a park and a bank requiring provision ofnatural turfs. The method of growing the turf of the invention can beemployed for protecting and greening various concrete walls and forimproving scenery. The method of laying the turf sheet structure of theinvention can be applied to a project for laying natural turfs atvarious facilities, and particularly for laying natural turfs on demandat large-scale facilities such as a large domed stadium.

What is claimed is:
 1. A plant growth sheet structure for growing aplant, comprising: a core layer and a seed holding layer on top of abase web layer, wherein (a) said core layer (1) has structure integrity,(2) is gas and water permeable by virtue of gaps provided therein; and(3) has a plurality of flexible plant protection projections on thesurface thereon, wherein (b) said base web layer is water retentive,with said core layer, said seed holding layer, and said base web layerbeing coupled together by the flexible plant protection projectionswoven through said base web layer to prevent decomposition of the plantgrowth sheet structure, and wherein (c) said seed holding layer isformed from a material different than either said core layer or saidbase web layer by the flexible plant protection projections woventhrough said base web layer to prevent decomposition of the plant growthsheet structure.
 2. The plant growth sheet structure of claim 1, whereina plurality of said flexible plant protection projections form a turf.3. The plant growth sheet structure of claim 1, wherein said seedholding layer for holding and germinating plant seeds is situatedbetween said core layer and said base web layer.
 4. The plant growthsheet structure of claim 3, wherein a plurality of said flexible plantprotection projections form a turf.
 5. The plant growth sheet structureof claim 3, wherein said plant seeds are grass seeds.
 6. A plant growthsheet structure for growing a plant, comprising the following layers inascending order: (1) a base web layer which is water retentive; (2) acore layer having structural integrity which is gas and water permeableby virtues of gaps provided therein; (3) a plant seed holding layer forholding and germinating plant seeds; (4) a cover web layer for allowinggrowth of plants from said plant seeds therethrough with the surface ofsaid cover web layer having flexible plant protection projectionsthereon; wherein the layers (1)-(4) are coupled together by the flexibleplant protection projections woven through said base web layer, corelayer, plant seed holding layer and cover web layer to preventdecomposition of the plant growth sheet structure, and wherein saidplant seed holding layer is formed from a material different than saidbase web layer or said core layer by the flexible plant protectionprojections woven through said base web layer, core layer, plant seedholding layer and cover web layer to prevent decomposition of the plantgrowth sheet structure.
 7. The plant growth sheet structure of claim 6,wherein said plant is a turf.
 8. The plant growth sheet structure ofclaim 6, wherein said plant seeds are grass seeds.
 9. The plant growthsheet structure of claim 6, wherein said plant protection projectionscomprise fiber members woven through said cover web layer into said baseweb layer.
 10. The plant growth sheet structure of claim 9, wherein saidfiber members have a water transferring property.
 11. The plant growthsheet structure of claim 9, wherein said fiber members are pile yarns,and said plant protection projections are pile or pile-like projections.12. The plant growth sheet structure according to claim 9, furthercomprising a backing member which at least partially prevents thedisengagement of portions of said fiber members forming said plantprotection projections woven into said base web layer.
 13. The plantgrowth sheet structure of claim 6, wherein said core layer is a meshcore layer.
 14. The plant growth sheet structure of claim 6, whereinsaid base web layer is a cotton layer comprising water-absorbing cotton.15. The plant growth sheet structure according to claim 9, wherein saidfiber members are pile yarns; said plant protection projections are pileor pile-like projections; said core layer is a mesh core layer; saidbase web layer comprises water-absorbing cotton.
 16. The plant growthsheet structure of claim 9, wherein said plant seed holding layercomprises (a) a non-woven fabric sheet allowing germination andsubsequent growth of the plant seeds which are uniformly dispersed onsaid non-woven fabric sheet; and (b) a water-soluble seed retaining filmcovering said plant seeds without preventing the germination andsubsequent growth of said plant seeds.
 17. The plant growth sheetstructure of claim 9, wherein said structure is flexible allowingrolling thereof.
 18. The plant growth sheet structure of claim 9,wherein said plant seed holding layer holds grass seeds.
 19. A turfgrowing method, comprising the following steps: (1) laying asemi-artificial turf sheet structure, which comprises: a plant growthsheet structure for growing a plant, comprising: a core layer and a seedholding layer on top of a base web layer, wherein said core layer hasstructure integrity, is gas and water permeable by virtue of gapsprovided therein; and has a plurality of flexible plant protectionprojections on the surface thereon, wherein said base web layer is waterretentive, with said core layer said seed holding layer and said baseweb layer being coupled together by the flexible plant protectionprojections woven through said base web layer to prevent decompositionof the plant growth sheet structure, and said seed holding layer isformed from a material different than either said core layer or saidbase web layer, on a concrete wall surface and thereafter (2) supplyingwater optionally containing nutrients to said semi-artificial turf sheetstructure.
 20. The turf growing method of claim 19, wherein saidconcrete wall surface is a concrete wall surface of a concrete dam. 21.The turf growing method of claim 19, wherein said concrete wall surfaceis a concrete wall surface of a retention pond.
 22. A turf growingmethod of claim 19, wherein said semi-artificial turf sheet structurecomprises a plurality of plant growth sheet structures, which plantgrowth sheet structure comprises the following layers in ascending order(1) a base web layer which water retentive; (2) a plant seed holdinglayer for holding and germinating plant seeds; and (3) a core layer,which is gas and water permeable by virtue of gaps provided therein,having structural integrity, wherein said core layer has flexible plantprotection projections on the surface thereon; with the layers (1)-(3)coupled together by the flexible plant protection projections woventhrough said base web layer, core layer and plant seed holding layer toprevent decompositon of the plant growth sheet structure, wherein saidcore layer optionally has turfs growing on the surface.
 23. A turfgrowing method of claim 19, wherein said semi-artificial turf sheetstructure comprises a plurality of plant growth sheet structures, whichplant growth sheet structure comprises the following layers in ascendingorder: (1) a base web layer is water retentive; (2) a core layer, whichis gas and water permeable by virtue of gaps provided therein, havingstructural integrity; (3) a plant seed holding layer for holding andgerminating plant seeds; and (4) a cover web layer allowing growth ofplants from said plant seeds therethrough, wherein said cover web layerhave flexible plant protection projections on the surface thereof; withthe layers (1)-(4) coupled together by the flexible plant protectionprojections woven through said base web layer, core layer, plant seedholding layer and cover web layer to prevent decompositon of the plantgrowth sheet structure, wherein said cover web layer optionally hasturfs growing on the surface.
 24. A method of utilizing turf sheetstructure in large-scale facilities said turf sheet capable of repeatedinstallation and removal from the large-scale facilities, said method,comprising the following steps: (a) laying a semi-artificial turf sheetstructure at an outdoor accommodating place located outside saidlarge-scale facilities, which semi-artificial turf sheet structurecomprises an artificial turf portion and a natural turf portion having agrowing turf; (b) maintaining said semi-artificial turf sheet structureat said outdoor accommodating place; (c) transferring saidsemi-artificial turf sheet structure to said large-scale facilities ondemand by laying said semi-artificial turf sheet structure on saidlarge-scale facilities; and thereafter (d) transferring saidsemi-artificial turf sheet structure from said large-scale facilities toan accommodating place outside said large-scale facilities and,thereafter, laying said semi-artificial turf sheet structure on saidaccommodating place.
 25. A method of removing a semi-artificial turfsheet structure from large-scale facilities and maintaining thesemi-artificial turf sheet structure removed, which semi-artificial turfsheet structure comprises an artificial turf portion and a natural turfportion having a growing turf said method comprising: transferring saidsemi-artificial turf sheet structure from said large-scale facilities toan accommodating place outside said large-scale facilities and,thereafter, laying said semi-artificial turf sheet structure on saidaccommodating place; and returning said semi-artificial turf sheetstructure to said large-scale facilities on demand by laying saidsemi-artificial turf sheet structure on said large-scale facilities. 26.The method of claim 24, wherein said large-scale facilities are sportfacilities or gymnasium.
 27. The method of claim 25, wherein saidlarge-scale facilities are sport facilities.
 28. The method of layingturf sheet structure of claim 24, wherein said semi-artificial turfsheet structure comprises a plurality of semi-artificial turf sheetpieces.
 29. The method of laying turf sheet structure of claim 24,wherein said outdoor accommodating place is an outer wall and/or a roofof said large-scale facilities.
 30. The method of laying the turf sheetstructure of claim 24, wherein said outdoor accommodating place is anouter wall and/or a roof of a building neighboring to said large-scalefacilities.
 31. The method of laying the turf sheet structure of claim24, wherein said semi-artificial turf sheet structure comprises aplurality of plant growth sheet structures, each of which comprises thefollowing layers in ascending order (1) a base web layer which is waterretentive; (2) a plant seed holding layer for holding and germinatingplant seeds; and (3) a core layer which is gas and water permeable byvirtue of gaps therethrough having structural integrity, wherein saidbase web has flexible plant protection projections on the surfacethereof; with the layers (1)-(3) coupled together by the flexible plantprotection projections woven through said base web layer, core layer andplant seed holding layer to prevent decomposition of the plant growthsheet structure, wherein said core layer optionally has a turf growingon the surface.
 32. The method of laying the turf sheet structure ofclaim 24, wherein said semi-artificial turf sheet structure comprises aplurality of plant growth sheet structures, each of which comprises thefollowing layers in ascending order (1) a base web layer which is waterretentive; (2) a core layer, which is gas and water permeable by virtueof gaps provided therein, having structural integrity; (3) a plant seedholding layer for holding and germinating plant seeds; and (4) a coverweb layer allowing growth of plants from said plant seeds therethrough,which cover web layer has flexible plant protection projections on thesurface thereof with layers (1)-(4) are integrally coupled together bythe flexible plant protection projections woven through said base weblayer, core layer, plant seed holding layer and cover web layer toprevent decomposition of the plant growth sheet structure, wherein saidcover web layer optionally has a turf growing on the surface.
 33. Themethod of claim 24, wherein said large-scale facilities are golfcourses.
 34. The method of claim 25, wherein said large-scale facilitiesare gymnasiums.